neck problem

i'm a newbie, so bear with me, ok
i just got an old bass, 4 strings, with frets, which is cool for me, coz i'm just exploring for now.. never played bass before in my life..
so i bought the strings, and started to string em up on my bass.. when i stringed up the first wire (it was an E string) i noticed that it touches first 4 or 5 frets.. so when i play that string without touching the fret board, i get a sound of metal brushing against metal (string, against frets)...
i tried to make the bridge higher, but it just doent do it, coz no matter how high i put the bridge, the string still touches frets..
i noticed that the neck is kinda popping out in the middle instead of being straight... is there a way to fix that, so the strings dont touch the frets?
i read there is a kinda spike inside the neck that can straighten up the neck... what do i do?
and oh yea, i got a lyon by washburn bass if that helps

From the way I read your post, it sounds like you have only replaced the E string. If so, did you already remove the other strings? The neck needs the tension of all four strings at pitch before you can figure out the proper relief.

If you have all four strings on it tuned to pitch and still have this issue, THEN, see the advice above.

Chasarms is right. Put on all strings. Then you,ll see if the neck needs adjustment. Look down the fingerboard from the head to the body and see if the neck is straight or if you have any bend. If the middle of the neck is bendig up, you need to loosen your trust rod